Sonobuoys are devices which are deployed into the ocean for detecting the presence of submarines or other underwater vessels by either listening for noise generated by the submarine or by emitting a sonar type signal and listening for a return echo. By deploying a number of sonobuoys in a particular fashion, a given area can be essentially cordoned off and any submerged vessels within that area detected. Generally, the most efficient means for deploying such sonobuoys are by launching from helicopters or fixed-wing aircraft which may deploy the buoys and loiter in the area to monitor the signals issued from the buoys and mark the location of any vessels detected. In addition to sonobuoys, other buoys may be deployed by aircraft, such as marker buoys which provide a smoke or a coloring agent along the ocean surface for position reference, or chaff buoys which may generate a cloud of metallic particles along the surface of the ocean for diverting radar guided devices away from the aircraft or friendly ships. All these buoys are cylindrically shaped having a generally common diameter of about 5 inches and are generally available in 1, 2 and 3 foot lengths, depending on the type of buoy required for a particular application.
Deploying the various buoys may include the steps of selecting the type of buoy, setting any particular parameters such as time delays, frequencies, or the like, loading the buoy into a deployment compartment and launching the buoy over the desired location. With conventional launching systems, the foregoing steps of selecting, setting and loading are generally performed while the aircraft is still on the ground as there is typically no access to the buoys once airborne. Conventional launching systems are usually of the pneumatic or explosive cartridge type, with the pneumatic systems employing gas pressure to charge a buoy containing tube, with the gas pressure propelling buoy away from the aircraft, and the cartridge system utilizing an explosive charge for propelling the buoy. Such systems do not provide for mission flexibility, as once loaded and airborne, the mission is either executed as planned or aborted.
An alternative to the pneumatic and cartridge systems includes gravity launch systems which simply drop the buoy through a chute from the bottom of the aircraft. Such gravity feed systems have included spring loaded trap doors which open in response to the weight and momentum of the buoy, allowing the buoy to free fall to the ocean surface. Such systems have been limited to low air speed operation in order to avoid contact of the buoy with aft structures on the aircraft during discharge. For example, antennas, landing gear and rear airfoil stabilizers may be damaged if the forward air speed allows the buoy to contact these surfaces during discharge. Utilizing a spring-loaded door, biased in the closed position, slows the initial descent velocity of the buoy, further increasing the potential for contact. Consequently, this system requires a further reduction in forward air speed to provide a margin of safety. The gravity systems are also similar to the pneumatic or cartridge type systems, requiring preselecting functions and loading the buoys while on the ground and therefore have not added to mission flexibility.
Consequently, the search continues for buoy deployment systems which maximize flexibility in the type of buoy to be discharged without requiring landing and reloading of the aircraft, while minimizing space requirements.